MSc Student
Advisor: Gerhard Steiner

Unit for Integrative Zoology, Department of Evolutionary Biology
University of Vienna

Abstract

Cystoisospora suis, a porcine apicomplexan parasite, causes severe economic losses in the livestock industry worldwide. It is characterized by a complex life cycle, with asexual and sexual development in the epithelium of the host gut and an environmental phase as oocyst. All parasite stages vary greatly in their morphology and function during the life cycle and presumably excrete different bioactive molecules as intercellular communication cargo. Due to the complexity of the parasite’s development we hypothesize that the cargo transported by parasite extracellular vesicles (EVs) varies with the life cycle stage. Hence, this study aimed to characterize EVs of all developmental stages of C. suis.

Parasite stages were obtained from intestinal porcine epithelia cell cultures (IPEC) during their respective expression and incubated for two hours in a host cell-free environment. All EVs were obtained by several centrifugation steps, and particle numbers and size distributions of stage-specific parasite EVs were analysed by nanoparticle tracking analysis (NTA). Transmission and scanning electron microscopy were used to visualise the respective EVs locations on the developmental stage. Furthermore, correlations between the lipidomic profile of EVs derived from C. suis asexual and sexual stages and their Fourier-transform infrared (FTIR) spectra were compared with profiles of other apicomplexan species.

Asexual, sexual and transmissible stages of C. suis expressed different EVs during the parasite’s life cycle. In addition, we could show that the EVs of asexual and sexual stages, which occur in the host animal, are more similar to each other than to the transmissible environmental stage, the oocyst. We could also show a cargo of polysaccharides, which are known to influence the conversion of parasite stages, and the occurrence of fatty acids in EVs, which presumably down-regulate the toxic activity of parasites. This study presents the first characterization of C. suis EVs and links them with the respective developmental stages of the parasite and putative functions.